Four and a half months after its launch on a Proton-M rocket from the Baikonur Cosmodrome in Kazakhstan, Northrop Grumman’s Mission Extension Vehicle has made history, successfully docking with its target satellite above Geostationary Orbit to extend that satellite’s lifetime well beyond the original plan.
The successful maneuver marked a groundbreaking change in how satellites are operated in orbit, with the Mission Extension Vehicle capable of not just extending a satellite’s life but also moving defunct satellites to safer orbits.
Speaking of the event, Tom Wilson, President, SpaceLogistics LLC, said, “Our Mission Extension Vehicle (MEV-1) provides an innovative, satellite life extension service. Together, Northrop Grumman, SpaceLogistics LLC, and Intelsat have taken the first step in pioneering in-space logistics services for both commercial and government customers.”
Mr. Wilson thanked Intelsat for their confidence in the MEV system, adding “For years we heard customers say ‘if you were here, we’d use you.’ Now we’re here.”
After that, Northrop Grumman controllers began a series of engine burns to raise MEV-1’s orbit from its highly elliptical Geostationary Transfer Orbit up to a circular orbit 300 km above the geosynchronous belt.
Geosynchronous Orbit (GEO) resides at an altitude of 35,786 km above Earth sea level.
Dying GEO satellites are routinely decommissioned and moved out of GEO into what is known as the GEO graveyard located 300 km above the main GEO belt.
The original GEO location of Intelsat 901. (Credit: Intelsat)
This graveyard is a stable orbit location that does not noticeably degrade due to atmospheric drag from Earth, and it’s where MEV-1 placed itself successfully on 1 February 2020.
Two months after the MEV’s launch, though, Intelsat began the process of decommissioning satellite Intelsat 901, formally removing it from service in December 2019 and transferring telecommunication customers to other satellites in its fleet.
Intelsat 901 was in the 330.5° East GEO location inclined 1.5° north of the equator.
After this decommissioning, Intelsat 901 was commanded to fire its thrusters to move itself into the GEO graveyard orbit. This satellite was chosen for the first MEV mission because it only had a “few months” of propellant life left according to Intelsat.
Intelsat 901 reached proximity with MEV-1 on 5 February 2020.
Over the following 19 days, MEV-1 performed a series of “practice” approaches to Intelsat 901, verifying its ability to autonomously approach and retreat from its target and to calibrate and fine-tune its sensors.
With all those capabilities verified, MEV-1 performed the rendezvous maneuver with Intelsat 901.
During approach, MEV-1 used a fleet of visual imagers, infrared cameras, and side scanning LIDAR to maintain complete awareness of its orientation and position relative to Intelsat 901.
After initially approaching to 80 m, MEV-1 initiated an autonomous hold while ground controllers verified all systems were ready to press to the next waypoint or hold location at 20 m.
After receiving the command from the ground to proceed, MEV-1 autonomously flew itself to the 20 m hold point before waiting again for ground controllers to ensure all was ready for the final press to the 1 m docking location.
Once MEV-1 was 1 m from Intelsat 901, it initiated station-keeping operations, holding itself rock-solid.
Northrop Grumman and Intelsat then each verified all was ready, with Intelsat giving the final “go” to proceed.
With that affirmation in hand, Northrop Grumman sent MEV-1 the command to dock.
MEV-1 autonomously reached out with its docking probe, that entered the nozzle of the liquid apogee engine on Intelsat 901.
The docking probe was inserted into the engine nozzle and through the “throat” — narrowest part of the engine nozzle.
Once the top of the probe was beyond the throat, it deployed a series of “fingers” to expand its size — like a wall anchor once inserted into a wall.
This allowed the docking probe to “grab” Intelsat 901 and pull it down onto three stanchions that now provide rigid support between the two craft, making them a single spacecraft.
MEV-1 completed this historic docking with Intelsat 901 on 25 February 2020 at 02:15 EST (07:15 UTC).
The combined spacecraft stack will now perform on-orbit checkouts before MEV-1 begins relocating the combined vehicle to return Intelsat 901 into service in late-March/early-April.
MEV-1 will now take Intelsat 901 to the 332.5° East GEO location over the central Atlantic and will change the satellite’s orbital inclination from 1.5° down to 0°.
The new location where Intelsat 901 will take over services for Intelsat 907. (Credit: Intelsat)
The 332.5° East location is currently occupied by Intelsat 907. The now-renewed Intelsat 901 will take over 907 service and seamlessly provide C-band service in the Americas, Europe, and Africa.
The linking of MEV-1 to Intelsat 901 marked the first time two objects docked together when one was never designed for docking.
It also marked the first time two commercial satellites docked in orbit and the first time mission extension services will be offered to a satellite in Geosynchronous Orbit.
In a statement, Mike DeMarco, Executive Vice President and Chief Services Officer at Intelsat, said, “We’re proud to make history with SpaceLogistics LLC and Northrop Grumman on this groundbreaking space milestone. Intelsat has been at the forefront of innovation and game-changing new space technology for decades. Pushing the boundaries of what’s possible is in our DNA here – that’s why we didn’t hesitate to sign up to be MEV-1’s first customer.”
Under the terms of the contract with Intelsat, MEV-1 will provide five years of life extension services to the Intelsat 901 satellite before returning the spacecraft to a final decommissioning orbit in the GEO graveyard.
MEV-1 will then move on to provide mission extension services to a new client spacecraft.
The Mission Extension Vehicle was designed and built at the Northrop Grumman’s Dulles, Virginia, facility and utilizes a “low-risk” mechanical docking system that attaches to existing features on the client satellite.
Once docked, MEV takes over the attitude and orbit maintenance of the combined vehicle stack to meet the pointing and station keeping requirements of the customer.
History in the making: Our MEV-1 has successfully docked with the @INTELSAT IS-901 satellite in orbit – a first for the industry. https://t.co/YgOmgwSq5Z pic.twitter.com/JyCJPn3gkG
— Northrop Grumman (@northropgrumman) February 26, 2020
The MEVs are designed for multiple dockings and undockings and can deliver over 15 years of life extension services.
A second MEV (MEV-2) is in final build and checkouts ahead of its planned launch later this year.
Because the MEV-1 docking went so well, MEV-2 will dock to its target satellite in GEO orbit without service interruption from the satellite to its customers.
Moreover, according to Northrop Grumman, this life extension service is the first step in an expansive technology development plan.
The company envisions a fleet of satellite servicing vehicles that not only extend the life of satellites but provide other services such as inclination changes and spacecraft inspections.
Future MEVs will also utilize advanced robotics technology to perform additional functions such as in-orbit repair and assembly.
During a teleconference this afternoon, Northrop Grumman stated they were not yet ready to talk about the robotics technology, but that additional information on this would be released in the coming months.
Moreover, Northrop Grumman confirmed this type of technology could be used in Low Earth Orbit to help clean up orbital debris. However, Mr. Wilson cautioned that “At this point in time, the market isn’t focused on LEO. But our technology would certainly apply there if that market develops.”